In various industries such as the food industry, the chemical industry, and the electronic industry, apparatuses for mixing powder raw materials and liquid raw materials are used. In, for example, bread making, for the purpose of gelatinizing starch in processes of shaping and baking products, and for the purpose of organizing gluten for raising, the mixing of flour and water is a necessary and indispensable process. In noodle making, for the purposes of shaping products and organizing gluten for achieving good texture, the process of mixing flour and water is indispensable.
In terms of the mixing process, prior arts have a major problem. Before discussing such a problem, descriptions need to be given of gluten synthesized by adding water to flour and the importance of the organization.
Gluten is a material having both viscoelasticity and adhesiveness, and is generated when protein, which accounts for 6-15% of flour (this varies with the variety), is hydrated. Kneading dough that contains hydrated gluten bonds gluten molecules to each other, thereby forming a huge three-dimensional net-like organization.
The quality of wheat food such as bread and noodles depends largely on a gluten organization. In the case of bread, gluten controls how the bread is raised in response to the action of yeast, and determines texture. In the case of noodles, gluten is a main factor in what is called “koshi (sturdiness)” and “tsurumi (feeling of food or drink traveling down the throat)”, and is also the most important factor in taste. To form a good organization, it is essential to first transfer all protein within wheat into gluten, and, for this reason, it is extremely important to spread water equally throughout in the mixing of wheat and water.
The following will describe a conventional general mixing method and problems thereof. To make noodles, batch-type mixers are often used. However, there is an unavoidable problem wherein gluten is synthesized and is simultaneously destroyed. In agitation mixing, mixing starts in one portion and then gradually spreads throughout. At positions where hydration initially occurs, gluten is immediately synthesized. Then, the gluten forms three-dimensional net-like organizations while capturing starch granules accounting for a majority of flour constituents. However, for positions where hydration is delayed, agitation needs to be continued. The mechanical action disadvantageously destroys gluten net-like organizations (which are actually weak). Moreover, this is fatal because destroyed gluten net-like organizations are unrenewable. That is, there is a contradiction wherein it is difficult to achieve both the completing of mixing and the forming of ideal gluten organizations.
As organizing progresses, viscidity increases and thus decreases fluidity, and heat is generated, thereby damaging the quality. Hence, equal hydration cannot be achieved by performing agitation alone.
Accordingly, a technique has been used wherein what is called “maturation”, in which aging, remixing, and enlarging are repeated in turn, is performed in the subsequent process, and water is made to permeate by taking time and trouble. The process naturally becomes excessively long, and, for quality-oriented luxury items and thin noodles such as somen, several days are required for the process of fabrication. This requires large-scale equipment and space and many hands, and the fabrication cost becomes high as a matter of course.
For mass-produced products, costs are focused on, and hence a high-speed rotation mixer enabling continuous production is often used instead of a batch-type mixer. A representative example of that scheme is a high-speed mixer described in patent document 1.
An exemplary improved continuous mixer is a mixer described in patent document 2. The mixer apparatus drops filmy water on a powder layer spread out on a rotating disk and agitates and mixes them.
Patent documents 3 and 4 are known as other prior arts. The technology of patent document 3 relates to an apparatus that coats particulate matter such as plant seeds with a liquid such as oil or fat. The apparatus of patent document 3 supplies particulate matter to the center of a rotating disk from above, spreads it out on the disk, and causes liquid to flow down to the disk or sprays liquid thereon, thereby achieving continuous coating. The apparatus could possibly be used as an apparatus for mixing with liquid raw material by supplying powder raw material instead of particulate matter. To achieve homogeneous mixing for hydrating protein particles, it is essential to maintain exactly constant the flow rate of powder raw material supplied to the center of the rotating disk and to achieve a completely even flow in all directions.
In patent document 4, a powdery material is fed at a definite rate to the center of a disk, which is rotating at a moderate speed, to form a thin powder layer close to the periphery of the disk. On the other hand, a sprayer rotating at high speed is provided on the same axis as the rotating disk and a liquid material, which is fed at a definite rate, is continuously sprayed and radiated thereby. Thus, the liquid material is sprayed at a high speed from behind onto the powder layer flow having been spread on the rotating disk. As a result, a homogeneous and instantaneous bond is continuously formed at the micro level between these materials so that a homogeneous mixture of the powdery material with the liquid material can be continuously obtained. By homogeneously mixing the powdery material with the liquid material from the beginning, agitation becomes unnecessary, which makes it possible to prevent the mixture from denaturation in the qualities thereof. Moreover, it becomes possible to remarkably shorten the process and simplify the apparatus. In the case of using in mixing a powder material mainly comprising wheat flour with a liquid material mainly comprising water, in particular, the apparatus or the method as described above makes it possible to produce bread or noodles with excellent qualities by a shortened and simplified process.